The vulnerability of Greenland’s glaciers to global warming is even greater than feared, according to radar and satellite data analysed by U.S. research scientists—and that’s bad news for rising sea levels.

“The collapse of large parts of the ice sheet in West Antarctica appears to have begun and is almost certainly unstoppable, with global warming accelerating the pace of the disintegration,” The New York Times reports two groups of scientists stated Monday.

Warming temperatures have reduced the area of frozen sea on the planet to roughly 2.2 million square miles, less than half of what it was four decades ago, suggesting that irreversible and accelerated climate change will be upon us in the coming decades.